JP2000059676A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image pickup device which improves vertical resolution and dynamic resolution in the case of non-interlace image pickup. SOLUTION: Light from an object is converted to an electric signal by a CCD through a lens 1 and a diaphragm 2. Then, this signal is written through a camera signal processing part 5 into memories 6a and 6b for each frame. Read from the memory is controlled and the signal is converted to an interlaced signal. The time of exposure through the CCD 3 is controlled so as to be a prescribed term shorter than a one-field term and the diaphragm 2 is controlled so that average luminance can become a target value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus using a single-plate image pickup means.

[0002]

2. Description of the Related Art In recent years, there has been a demand for higher image quality in electronic cameras.
In electronic still cameras, the number of pixels in the VGA class has become common. Also, the CCD, which is an image sensor, is of a so-called progressive type that can read all pixels independently, and the quality of the image has been improved. A non-interlaced (progressive) image has a higher vertical resolution than an image captured by the interlaced method, and is clear as a still image. Could not be displayed. Means for solving this is disclosed in, for example, Japanese Patent Application Laid-Open No. S61-159883.
Hereinafter, this conventional imaging apparatus will be described.

FIG. 5 is a block diagram showing a conventional image pickup apparatus. In FIG. 5, the imaging device is a TV camera 51.
The video signal is input to the frame memory via the switch 52. The memory control unit 55 includes the switches 52 and 5
6, the frame memories 53, 54
It controls writing to and reading from the memory.

[0004] Next, the operation of the image pickup apparatus configured as described above will be described. The video signal obtained from the TV camera 51 by the non-interlace method is transmitted to the frame memory 53 via the switch 52 based on a command from the memory control unit 55, and the video signal of the m + 1th frame is supplied to the frame memory 53. The data is stored in the frame memory 54. During the period in which the (m + 1) th frame is stored, the video signal stored in the (m) th frame is converted from a non-interlaced to an interlaced video signal by the memory control unit 55 and output via the switch 56. In the next frame, the switches 52 and 56 are switched, and the video signal of the (m + 1) th frame is converted into an interlaced video signal and output.

[0005]

However, in the above-described conventional configuration, a 30-frame non-interlaced video signal is converted into a 60-field interlaced video signal format. That is, TV
Since the non-interlaced video signal output from the camera is a signal exposed for one frame period (1/30 second), even if the vertical resolution of a moving image is improved by non-interlaced imaging, the field period (1/60) is used. Seconds) The moving image resolution was inferior to that of the exposed video signal, and the moving image had defects.

An object of the present invention is to solve the above-mentioned conventional problems, and it is an object of the present invention to realize an imaging apparatus having a high vertical resolution and a high dynamic resolution when performing non-interlaced imaging.

[0007]

According to a first aspect of the present invention, there is provided a lens for forming an image of a subject on an imaging surface, a diaphragm which is a part of the lens and adjusts the amount of light incident on the imaging surface, Imaging means for photoelectrically converting image information on the imaging surface and sequentially reading out non-interlace in one frame period; gain adjustment means for adjusting a gain of a signal from the imaging means; and a signal whose gain has been adjusted by the gain adjustment means. And a signal processing unit that generates a video signal by performing constant signal processing on the image signal and generates an average luminance signal indicating the brightness of the entire screen. Controlling, exposure control means for adjusting the exposure using the aperture based on the information of the average luminance signal, storage means for storing a video signal output from the signal processing unit,
Signal converting means for alternately reading even-numbered fields and odd-numbered fields of the video signal stored in the storage means and converting the same into an interlaced signal.

According to a second aspect of the present invention, in the image pickup apparatus of the first aspect, the exposure control means adjusts the exposure with the aperture when the brightness of the subject is within a range in which the exposure can be controlled by the aperture. In the case where the exposure cannot be adjusted by the aperture, the exposure is adjusted by amplifying a signal from the imaging unit so that the gain of the gain adjustment unit is increased in addition to the exposure adjustment by the aperture. Things.

According to the present invention, the exposure control means controls the imaging means so that the exposure time becomes a fixed period shorter than one field period, and adjusts the exposure with the aperture according to the brightness of the subject. It is possible to realize good image quality with high vertical resolution and high dynamic resolution.

According to a third aspect of the present invention, there is provided a lens for forming a subject image on an imaging surface, imaging means for photoelectrically converting image information on the imaging surface and sequentially reading out non-interlace in one frame period; Gain adjusting means for adjusting the gain of the signal from the means, and applying a constant signal processing to the signal gain-adjusted by the gain adjusting means to generate a video signal, and generating an average luminance signal indicating the brightness of the entire screen. A signal processing unit to generate, and changing an exposure time of the imaging means within an arbitrary period of one field period or less according to the brightness of the subject so that an average luminance becomes a predetermined value. Exposure control means for controlling, storage means for storing a video signal output from the signal processing unit, and reading of the video signal stored in the storage means in an even field and an odd field alternately. To leave those characterized by comprising signal converting means for converting the interlaced signal.

According to a fourth aspect of the present invention, in the imaging apparatus according to the third aspect, the exposure control means can adjust the exposure so that the average luminance becomes a predetermined value in a period of one field period or less. Is characterized in that a signal from the imaging means is amplified and exposure adjustment is performed so that the gain of the gain adjustment means is increased.

According to a fifth aspect of the present invention, there is provided a lens for forming an image of a subject on an imaging surface, a diaphragm which is a part of the lens and adjusts the amount of light incident on the imaging surface, and an image on the imaging surface. Imaging means for photoelectrically converting information and sequentially reading out non-interlaced data in one frame period; gain adjustment means for adjusting the gain of a signal from the imaging means; and performing constant signal processing on the signal adjusted by the gain adjustment means. Signal processing unit for generating an average luminance signal indicating the brightness of the entire screen, a motion detection unit for detecting motion information of a subject on the imaging plane, and a video signal of the average luminance signal. Exposure control means for adjusting the exposure time of the imaging means, the aperture, and the amplification amount of the gain adjustment means from the information and the information of the motion detection means; storage means for storing a video signal output from the signal processing unit; Storage means even field the stored the video signal to, and is characterized in that it comprises a signal conversion means for converting the odd field is read alternately interlaced signal.

According to a sixth aspect of the present invention, in the imaging apparatus of the fifth aspect, the motion detecting means extracts a motion vector from information of a luminance signal output from the signal processing unit. The control means sets the exposure time of the imaging means to be shorter as the magnitude of the motion vector extracted by the motion detection means increases, and determines the set value of the aperture so as to have a predetermined average luminance. It is characterized by the following.

According to a seventh aspect of the present invention, there is provided a lens for forming an image of a subject on an image pickup surface, and a diaphragm which is a part of the lens and opens and closes the light incident on the image pickup surface and adjusts the amount of incident light. Imaging means for photoelectrically converting image information on the imaging surface and sequentially reading out the image information in a non-interlace manner during one frame period; gain adjustment means for adjusting the gain of a signal from the imaging means; and gain adjustment by the gain adjustment means. A signal processing unit for performing a constant signal processing on the signal to generate a video signal and generating an average luminance signal indicating the brightness of the entire screen; Exposure control means for controlling opening and closing, changing the aperture diameter of the aperture according to the brightness of the subject based on the information of the average luminance signal, and writing a video signal output from the signal processing unit. Is characterized in that it comprises storage means for the storage means even field the stored the video signal to a signal converting means for converting the interlaced signal odd field is read out alternately, a.

According to an eighth aspect of the present invention, in the imaging apparatus of the seventh aspect, the exposure control means increases the gain of the gain adjustment means when the subject is dark and the exposure cannot be adjusted by the aperture diameter of the aperture. The exposure control is performed by amplifying the signal from the image pickup means so as to increase the size.

[0016]

(First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an overall block diagram of an imaging apparatus according to a first embodiment of the present invention. First, the flow of the video processing of the present invention will be described with reference to the drawings. The lens 1 forms a subject image on an imaging surface, and has a stop 2 for adjusting the amount of light. Light S1 from a subject is imaged on an imaging surface of a CCD 3, which is imaging means, by a lens 1 and a diaphragm 2 which is a part of the lens. A drive circuit and a motor (not shown) are used to drive the diaphragm 2.
One frame is photoelectrically converted by the CCD 3, and one frame is read out by a 1/30 second progressive scan, and is converted into a non-interlaced electric signal S2. The electric signal S2 is gained up by gain adjusting means, here AGC4. Next, the camera signal processing unit 5 separates the video into a non-interlaced luminance signal S3 and a color difference signal S4, and calculates an average luminance signal S7. The luminance signal S3 and the color difference signal S4 are given to the switch 9. The switch 9 performs switching on a frame-by-frame basis based on a signal from the memory control unit 7 so that the luminance signal S3A and the color-difference signal S
A4 writes to the memory 6a. The luminance signal S3B and color difference signal S4B of the (m + 1) th frame are written into the memory 6b.
The memories 6a and 6b are storage means for storing video signals for one frame, respectively. The data stored in the memory 6a is
While the data is stored in the memory 6b, the data is read out from the memory control unit 7 in a format in which the non-interlaced signal is converted into an interlaced signal, and output as the m-th frame interlaced luminance signal S5A and color difference signal S6A. . Similarly, the data stored in the memory 6b is
While the data is stored in the memory 6a, the data is read out in a format in which the non-interlaced signal is converted into an interlaced signal by the memory control unit 7, and output as the (m + 1) th frame interlaced luminance signal S5B and color difference signal S6B. . The signals S5A and S5B and S6A and S6B are time-series interlaced luminance signals S by the switch 10.
5 and a color difference signal S6.

On the other hand, the luminance signal S3 is integrated in the camera signal processing section 5, an average luminance signal S7 of the image is calculated, and output to the exposure control section 8. The exposure control unit 8 is an exposure control unit that controls the imaging unit so that the exposure time of the imaging unit is a certain period of one field period or less, and controls the aperture so that the average luminance becomes a predetermined value. That is, the exposure controller 8 first sets the exposure time of the CCD 3 to 1/60, for example.
A charge discharge pulse S8 is sent to the CCD 3 so as to reach the second.
The operation of the exposure control is performed by transmitting a control signal S9 so that the average luminance signal S7 becomes a preset target luminance, and opening and closing the aperture 2. If the target brightness is not reached even when the aperture 2 is opened to the maximum, a gain-up signal S10 is sent to the AGC 4 to control the brightness to the target brightness.

Although the camera signal processing section 5 performs processing for forming a luminance signal and a color difference signal, a circuit for performing processing for forming R, G, and B signals may be used. Also in this case, R, G, B
Exposure can be controlled by generating an average luminance signal from the above signals. The exposure controller 8 sets the exposure time of the CCD 3 to 1/60 second of one field period. However, the exposure time can be set arbitrarily as long as it is shorter than 1/60 second.
Particularly in an environment where fast-moving subjects frequently appear, it is necessary to shorten the exposure time. However, if the exposure time is set too short, the gain must be increased by the AGC 4 with the aperture open, even if the subject is not so dark, which may degrade S / N.

(Second Embodiment) Next, a second embodiment will be described. FIG. 2 is a block diagram showing an entire image pickup apparatus according to a second embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description is omitted. The second embodiment differs from the first embodiment in that the stop is not a constituent element, and the control method of the exposure control unit 28 is different. According to the present embodiment, the exposure control unit 28 sets the charge discharge pulse S28 to C so that the average luminance signal S7 has a preset target luminance.
The exposure time of the CCD 3 is changed within the range of one field exposure time or less. For example, when panning the camera from a bright place to a dark place,
When the subject is bright, the charge discharging pulse S28 is set so as to shorten the exposure time, and the charge discharging pulse S28 is changed so that the exposure time becomes longer as the subject becomes darker. If the target luminance is not reached when the exposure time reaches 1/60 second, the charge discharging pulse S28
From the exposure control by AGC4 to the control by AGC4.
A gain-up signal S20 is sent to the GC 4 to control the brightness to the target. In the present embodiment, the exposure time of one field period, that is, 1/60 seconds, is used as the control switching point. However, for the same reason as in the first embodiment, this switching time is set to a time shorter than 1/60 seconds. Can be set arbitrarily.

(Third Embodiment) Next, a third embodiment will be described. FIG. 3 shows an overall block diagram of an image pickup apparatus according to the third embodiment of the present invention, and the same parts as those in the first embodiment are denoted by the same reference numerals and detailed description is omitted. In the first and second embodiments of the present invention, the point is to make the exposure time approximately equal to that of the interlace in order not to lower the dynamic resolution.
It is desirable to use a method in which a moving subject is photographed with a short exposure time and a non-moving subject is exposed with a long exposure time so that the S / N is not deteriorated. Therefore, in the third embodiment, a motion detection unit 30 that detects the motion of a subject is provided. The motion detection section 30 compares the luminance signal S3 output from the camera signal processing section 5 with the luminance signal of the previous frame, detects a motion vector S32 indicating the amount and direction of the motion, and outputs the motion vector S32 to the exposure control section 38. The exposure control unit 38 determines the exposure time according to the absolute value of the motion vector. The exposure control unit 38 sets the charge discharge pulse S38 to shorten the exposure time if the absolute value of the motion vector is large, and to lengthen the exposure time if the absolute value of the motion vector is small. Output and CCD
3 is controlled. In this state, the control signal S33 first stops the diaphragm 2 so that the average luminance signal S7 reaches the target luminance.
To adjust. At this time, if the exposure is still insufficient even if the aperture is opened, the control is switched to AGC4 and the AGC
Then, a gain-up signal S30 is sent to 4 to control the brightness to the target. In the third embodiment, the exposure time is determined according to the movement of the subject, so that the dynamic resolution can be set to a favorable state. In the case of a subject with little movement, 1/6
Since the exposure time can be made longer than 0 second, an image having a relatively good S / N can be obtained.

(Fourth Embodiment) Next, a fourth embodiment will be described. FIG. 4 is a block diagram showing an entire image pickup apparatus according to a fourth embodiment of the present invention, and the same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description is omitted. In the first, second, and third embodiments described above, the exposure time of the CCD 3 is basically adjusted by the charge discharge pulse output from the exposure control unit.
In the fourth embodiment, the aperture 42 is provided with a mechanical shutter function to adjust the exposure time. The exposure control unit 48 generates a control signal S49 for causing the aperture 42 to open the aperture 42 for 1/60 seconds and to close the aperture 42 for 1/60 seconds in a cycle of 1/30 seconds. By controlling the diaphragm 42 using this control signal, the exposure time of the CCD 3 is substantially fixed at 1/60 second. In this state, the aperture 42 adjusts the brightness appropriately by applying a command to the control signal S49 to set the aperture diameter when the aperture 42 is open so that the average brightness signal S7 reaches the target brightness. . If the exposure is still insufficient even when the aperture is fully opened, the control is switched to AGC4, and a gain-up signal S40 is sent to AGC4 to control the brightness to the target. In the fourth embodiment, since the exposure adjustment is not performed by the charge discharge pulse in the CCD 3, the flicker occurs when a subject such as a fluorescent lamp is photographed, which is a problem when adjusting the exposure by the charge discharge pulse, and the depth of field is reduced. Thus, a high-quality image that does not cause discomfort or the like can be obtained.

[0022]

As described above, claims 1 to 4, 7, and
According to the eighth aspect of the present invention, there is provided an imaging apparatus having a high vertical resolution and a high dynamic resolution because the storage time of the image sensor can be controlled so as not to exceed one field period when performing non-interlace imaging with the above configuration. it can. According to the fifth and sixth aspects of the present invention, the exposure time is determined in accordance with the movement of the subject, so that the dynamic resolution can be improved. Further, when the movement of the subject is small, the exposure time can be set longer than one field period.
The effect of obtaining an image having an N ratio is obtained. According to the seventh and eighth aspects of the present invention, since the exposure adjustment is not performed by the imaging means, an effect is obtained in which an image which does not cause flicker when shooting a subject such as a fluorescent lamp or a sense of incongruity in the depth of the subject can be obtained. Can be

[Brief description of the drawings]

FIG. 1 is a block diagram of an imaging device according to a first embodiment of the present invention.

FIG. 2 is a block diagram of an imaging device according to a second embodiment of the present invention.

FIG. 3 is a block diagram of an imaging device according to a third embodiment of the present invention.

FIG. 4 is a block diagram of an imaging device according to a fourth embodiment of the present invention.

FIG. 5 is a block diagram of a conventional imaging device.

[Explanation of symbols]

 Reference Signs List 1 lens 2, 42 aperture 3 CCD 4 AGC 5 camera signal processing unit 6a, 6b, 53, 54 memory 7, 55 memory control unit 8, 28, 38, 48 exposure control unit 9, 10, 52, 56 switch 30 motion detection Part 51 TV camera

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C022 AA00 AB01 AB02 AB04 AB12 AB17 AB20 AB68 AC42 AC54 AC69 5C024 AA01 CA11 CA13 DA05 GA11 HA10 HA12 HA23 JA11

Claims (8)

[Claims] A lens that forms an image of a subject on an imaging surface; a diaphragm that is a part of the lens and adjusts the amount of light incident on the imaging surface; and a frame that photoelectrically converts image information on the imaging surface. Imaging means for sequentially reading out in a non-interlaced manner during a period; gain adjusting means for adjusting the gain of a signal from the imaging means; and performing a constant signal processing on the signal whose gain has been adjusted by the gain adjusting means to generate a video signal. A signal processing unit that generates an average luminance signal indicating the brightness of the entire screen; and controls the imaging unit so that an exposure time is a fixed period equal to or less than one field period, and based on the information of the average luminance signal, Exposure control means for adjusting exposure using an aperture; storage means for storing a video signal output from the signal processing unit; and storing the video signal accumulated in the storage means in an even field, an odd field, Imaging apparatus characterized by comprising a signal conversion means for converting field reads alternately interlaced signal. 2. The exposure control means adjusts exposure with an aperture when there is brightness of a subject within a range in which exposure control by the aperture is possible, and adjusts the exposure with the aperture when the exposure cannot be adjusted by the aperture. 2. The image pickup apparatus according to claim 1, wherein a signal from said image pickup means is amplified and exposure adjustment is performed so that a gain of said gain adjustment means is increased in addition to exposure adjustment. A lens for forming a subject image on an imaging surface; an imaging unit for photoelectrically converting image information on the imaging surface and sequentially reading out the image information in a non-interlace manner during one frame period; and a gain of a signal from the imaging unit. A gain adjustment unit for adjusting, and a signal processing unit that generates a video signal by performing constant signal processing on the signal whose gain has been adjusted by the gain adjustment unit, and generates an average luminance signal indicating the brightness of the entire screen, Exposure control means for controlling the exposure time of the imaging means by changing the exposure time of the imaging means within an arbitrary period of one field period or less according to the brightness of the subject so that the average luminance becomes a predetermined value, A storage unit for storing a video signal output from the signal processing unit; and interlacing the video signal stored in the storage unit by alternately reading even and odd fields. An image pickup apparatus, comprising: 4. The exposure control means, wherein when the exposure cannot be adjusted so that the average luminance becomes a predetermined value in an exposure time period of one field period or less, the image pickup is performed such that the gain of the gain adjustment means is increased. 4. The image pickup apparatus according to claim 3, wherein the signal from the means is amplified to adjust the exposure. 5. A lens that forms a subject image on an imaging surface, a diaphragm that is a part of the lens and adjusts the amount of light incident on the imaging surface, and one frame that photoelectrically converts image information on the imaging surface. Imaging means for sequentially reading out in a non-interlaced manner during a period; gain adjusting means for adjusting the gain of a signal from the imaging means; and performing a constant signal processing on the signal whose gain has been adjusted by the gain adjusting means to generate a video signal. Together with a signal processing unit that generates an average luminance signal indicating the brightness of the entire screen, a motion detection unit that detects motion information of a subject on the imaging surface, and information of the average luminance signal and the motion detection unit. From the information, the exposure control means for adjusting the exposure time of the imaging means, the aperture, and the amplification amount of the gain adjustment means, a storage means for storing a video signal output from the signal processing unit, The even video signal field, an imaging apparatus characterized by comprising signal converting means for converting the odd field is read alternately interlaced signal, was. 6. The motion detecting means for extracting a motion vector from information of a luminance signal output from the signal processing unit, and the exposure control means includes: 6. The imaging apparatus according to claim 5, wherein the exposure time of the imaging unit is set to be shorter as the size increases, and the aperture setting value is determined so as to have a predetermined average luminance. 7. A lens that forms a subject image on an imaging surface, a diaphragm that is a part of the lens, that opens and closes incidence on the imaging surface, and adjusts the amount of incident light, and an image on the imaging surface. Imaging means for photoelectrically converting information and sequentially reading out non-interlace in one frame period; gain adjustment means for adjusting the gain of a signal from the imaging means; and performing a constant signal processing on the signal whose gain has been adjusted by the gain adjustment means. And a signal processing unit for generating an average luminance signal indicating the brightness of the entire screen, and controlling the opening and closing of the aperture so that the exposure time becomes a fixed period of one field period or less. Exposure control means for adjusting exposure by changing the aperture diameter of the aperture according to the brightness of the subject based on information of the luminance signal, and storage means for storing a video signal output from the signal processing unit, Serial memory means the even field stored the video signal to the image pickup apparatus characterized by comprising a signal conversion means for converting the interlaced signal odd field is read out alternately, a. 8. The exposure control means amplifies a signal from the imaging means so as to increase the gain of the gain adjustment means when the subject is dark and the exposure cannot be adjusted by the aperture diameter of the aperture. The imaging device according to claim 7, wherein the adjustment is performed.